‘Secret weapon’ Cameron will help Boris’s bid for the suburbs

David Cameron will hit the campaign trail for Boris Johnson after next week’s Budget in a bid to boost the Tory turnout in London’s suburbs.

The Prime Minister is being seen as the Mayor’s “secret weapon” in the crucial battle to win the outer doughnut where experts say the contest for City Hall will be won or lost.

Downing Street has been holding meetings over the past 18 months to decide how best to support Mr Johnson’s re-election campaign. The conclusion is that Mr Cameron should campaign in places such as Bromley where there are Tory supporters who can be mobilised by his appearance.

In particular, Mr Cameron will highlight the sums secured by the Mayor for big projects like the £16 billion Crossrail scheme, arguing that it is down to the fact that Mr Johnson is trusted by the Government and able to work with ministers.

“Part of Boris Johnson’s appeal is that he works constructively with central government and has managed to secure a string of good deals for Londoners, from Crossrail to police funding,” said a Downing Street adviser.

“Ken [Livingstone] could not work with the Government of the day. Even when Labour were in power, he would take them to court and there were mistrust between them and they tried to stop him running things.”

With Mr Johnson and Mr Livingstone neck and neck, election experts say turnout by Tory-inclined voters in the doughnut is decisive. In inner London, Mr Livingstone is ahead by 53 per cent to 47. But Mr Johnson has a narrow lead in the more populous outer circle, of 52 to 48 per cent. The Prime Minister is treating the London elections as the most important electoral challenge he will face this year. In a speech to Conservative backbenchers last autumn, he described victory in the capital as “essential” and said “keeping Boris in London was absolute priority”.

The stakes are high because Tories fear Mr Cameron and the economic slowdown would be blamed if Mr Johnson loses. The Mayor and Prime Minister have clashed over policy several times. Mr Johnson has attacked benefits cuts for risking “Kosovo-style ethnic cleansing” and backed an EU referendum.